1. Field of the Invention
This invention relates to a rotary electric machine having a rotary electric machine part, a switching circuit part for performing current control of this rotary electric machine part, and a heat-dissipating device for cooling multiple switching devices constituting this switching circuit part, and particularly to a rotary electric machine to be applied for example to a vehicle-mounted rotary electric machine provided with a power device unit for performing inverter control or the like.
2. Description of the Related Art
In related art, in a rotary electric machine such as a rotary electric machine for mounting in an automotive vehicle, a switching circuit part such as a power device unit for current-controlling a rotary electric machine part by inverter control or the like has been installed remotely from the rotary electric machine part. However, as a result of the switching circuit part (e.g. power device unit) and the rotary electric machine part being installed remotely from each other, the length of a.c. wires electrically connecting these together becomes long, the associated wiring resistance becomes large, and the associated voltage drop becomes large. Consequently, the problem has arisen that the torque of the rotary electric machine falls, or its rotational speed falls. Although the measure of making the wires thick to minimize the increase in wiring resistance is available, in this case weight and cost increase, and restrictions on weight and/or cost mean that there is a limit to how far this measure can be adopted.
Also, installing the switching circuit part (power device unit) and the rotary electric machine part remotely from each other means that a separate space for installing the switching circuit part (power device unit) is needed besides the space where the rotary electric machine part is installed. However, when the rotary electric machine is disposed in a confined space, for example in the engine compartment of a vehicle in which such a rotary electric machine is mounted in practice, it is sometimes difficult to provide a separate space for installing the switching circuit part (power device unit), and this can constitute a layout problem.
A rotary electric machine in which to solve these problems a power device unit (switching circuit part) constituting an inverter is mounted integrally with a rotary electric machine part is set forth in for example Patent Document 1. By the power device unit (switching circuit part) and the rotary electric machine part being integrated, it becomes possible to make the a.c. wiring connecting the two together short, and the associated voltage drop can be reduced. As a result, effects such as improvement of the torque characteristics and the speed characteristics of the rotary electric machine, or reduction of wiring weight, and increased noise resistance can be expected.
Patent Document 1: JP-A-2004-135447 (FIG. 1 and description thereof)
When the power device unit (switching circuit part) is mounted inside the casing of the rotary electric machine, as shown in Patent Document 1, heat-sinking of the switching devices is carried out by a cooling draft being made to flow into the casing by a fan rotating together with the rotor of the rotary electric machine. However, as a result of the power device unit being mounted inside the casing, the shape of the cooling draft flow passage becomes narrow and complicated. Consequently, the problem arises that pressure losses accompanying the flow of the draft increase, the cooling draft volume falls and cooling is not effected adequately, the temperature of the switching devices rises, and this results in breakdown of the switching devices. And, if an attempt is made keep the temperature of the switching devices within a tolerable range, measures such as making the cooling draft passage wide and increasing the cooling draft volume, or making the size of a heat sink large, become necessary, and these result in the problem that the rotary electric machine becomes large.
In a rotary electric machine to be installed in a confined space such as a rotary electric machine for mounting in an automotive vehicle, and particularly among these, in a rotary electric machine having a rotary electric machine part and a switching circuit part for performing current control of this rotary electric machine part and a heat-dissipating device for cooling multiple switching devices constituting the switching circuit part, when the rotary electric machine part and the switching circuit part for performing current control of this rotary electric machine part and the heat-dissipating device for cooling multiple switching devices constituting the switching circuit part are to be installed in a confined space, it is important that the conditions of weight, cost and installation space are taken into account and in particular that steps are taken to maximize cooling effect so that the rotary electric machine does not become large.